Ukraine's anti-monopoly body said on Friday it had given permission for Russia's VimpelCom cellphone firm to buy Ukrainian RadioSystems, a small firm whose purchase is strongly opposed by one of VimpelCom's shareholders.
The anti-monopoly committee said it would allow VimpelCom to buy over 50 percent of voting shares in URS.
Norway's Telenor, a VimpelCom shareholder that controls Ukraine's second-biggest mobile phone company, Kyivstar, opposes the $200 million purchase, saying it is a bad deal.
Telenor's opposition turned into a serious boardroom battle with VimpelCom's largest shareholder, Alfa Group, which says VimpelCom must expand into Ukraine because the Russian market is becoming saturated.
Alfa, however, has pushed for the Russian operator to expand into Ukraine, where subscriber growth rates are faster than at home.